Germline homozygous missense DEPDC5 variants cause severe refractory early-onset epilepsy, macrocephaly and bilateral polymicrogyria.

DEPDC5 (DEP Domain-Containing Protein 5) encodes an inhibitory component of the mammalian target of rapamycin (mTOR) pathway and is commonly implicated in sporadic and familial focal epilepsies, both non-lesional and in association with focal cortical dysplasia. Germline pathogenic variants are typically heterozygous and inactivating. We describe a novel phenotype caused by germline biallelic missense variants in DEPDC5. Cases were identified clinically. Available records, including magnetic resonance imaging and electroencephalography, were reviewed. Genetic testing was performed by whole exome and whole-genome sequencing and cascade screening. In addition, immunohistochemistry was performed on skin biopsy. The phenotype was identified in nine children, eight of which are described in detail herein. Six of the children were of Irish Traveller, two of Tunisian and one of Lebanese origin. The Irish Traveller children shared the same DEPDC5 germline homozygous missense variant (p.Thr337Arg), whereas the Lebanese and Tunisian children shared a different germline homozygous variant (p.Arg806Cys). Consistent phenotypic features included extensive bilateral polymicrogyria, congenital macrocephaly and early-onset refractory epilepsy, in keeping with other mTOR-opathies. Eye and cardiac involvement and severe neutropenia were also observed in one or more patients. Five of the children died in infancy or childhood; the other four are currently aged between 5 months and 6 years. Skin biopsy immunohistochemistry was supportive of hyperactivation of the mTOR pathway. The clinical, histopathological and genetic evidence supports a causal role for the homozygous DEPDC5 variants, expanding our understanding of the biology of this gene.

Status dystonicus in childhood.

BACKGROUND: Status Dystonicus is a rare complication of dystonia. It is a life threatening disorder that needs urgent treatment.The aim of this study is to describe clinical features, management and follow up of children with Status Dystonicus. METHODS: - We conducted a retrospective study over an 8-year period including all patients diagnosed with Status Dystonicus. Clinical characteristics, etiologies and management were analyzed. RESULTS: - Ten patients were included. Main features of Status Dystonicus were a severe generalized dystonia with vegetative signs. Laryngeal spasm and swallowing disorders were observed in 4 cases. Several treatments such as Levodopa, Anticholinergics, Baclofen, Benzodiazepines and Neuroleptics were tried. Mechanical ventilation was required in 4 cases. Two patients died due to rhabdomyolysis and respiratory failure. Others returned to their pre-Status Dystonicus. CONCLUSION: - Status Dystonicus is a life threatening condition that needs an urgent management on an intensive care unit. In fact, patients with Status Dystonicus can develop respiratory failure and metabolic complications.On the basis of our experience, we delineated a therapeutic approach in which the patient with Status Dystonicus needs supportive care, specific therapy of dystonia and intravenous sedative treatment.

Postencephalitic parkinsonism and selective involvement of substantia nigra in childhood.

Parkinsonism is a rare complication of encephalitis in childhood. Association to an isolated involvement of substantia nigra is exceptional. Mechanisms of nigral cells neurotropism remain hypothetic. We report on three children presenting with postencephalitic parkinsonism and selective involvement of substantia nigra, with literature review and we discuss pathogenic mechanisms.